1. Technical Field
This invention relates to radar sensors and, more particularly, to a compact, flexible, and built-in radiation structure for a millimeter wave radar sensor.
2. Discussion
Radar sensors are generally employed for detecting objects within a desired field. Typical sensing systems have been developed which employ radar, laser, infrared (IR), or ultrasonic principles. However, each of these systems has its drawbacks. Current radar sensors operate at frequencies which are too low to incorporate the advanced monolithic millimeter wave integrated circuit (MMIC) and compact patch antenna technology. Generally, these sensing units are bulky and difficult to integrate into a host system. In addition, current radar sensing units require a large number of components which make the units costly. As a result, these systems are limited in modularity and flexibility, and therefore, applications. Typical laser sensors generally suffer from high cost, in addition to potential health hazards. Futhermore, they are limited by environmental conditions such as fog and smoke. Infrared and ultrasonic sensors have limitations which include sensitivity to environmental interferences, as well as interference from other similar sources, in addition to noise.
There is a need for an effective compact, flexible and integrated radar sensor that can be easily integrated into many systems for various applications. In particular, there exists a need for a compact, low cost, flexible radar sensor for automotive and space and defense-related applications and the like. Such applications may include integrating such a radar sensor onto an automotive vehicle to provide a blind spot detector for crash avoidance purposes. For advanced vehicle designs, such as those involving four-wheel drive functions, there is a need for a smart sensor to determine the true ground speed of the vehicle for cruise control purposes, accurate vehicle speed measurement, and four-wheel steering. In addition, there exists a need for a smart sensor to determine the vehicle height and to project the road surface ahead for advanced adaptive suspension systems. Furthermore, for military applications, there exists a need for a compact, modular, low cost sensor for collision avoidance or armored vehicles, heavy robotic equipment and all types of transportation equipment during night operations and under adverse conditions such as fog and battle field smoke.
Sensor systems have been developed and provided for such applications. Typical systems have generally employed radar, laser, infrared, and ultrasonic sensors. However, these systems have not been widely deployed because of high cost, poor performance, excessive size, and limited flexibility.
It is therefore desirable to obtain an effective, low cost, compact and safe to operate radar sensor. It is further desirable to obtain such a radar sensor which can be easily integrated into various systems. Such a system may include an automotive vehicle for providing a blind spot detector, a true ground speed measuring device, a vehicle height measurement device, and other various applications.
Conventional methods for constructing a radar sensor use electronics and an antenna which are separate components. The electronics are typically packaged inside a sealed conductive box for environmental protection and electromagnetic shielding. The electronics and the antenna are then assembled. Another conventional method packages the electronics inside a horn antenna. Still another approach utilizes feed assemblies in combination with reflector or lens antenna systems. Such designs are bulky and expensive.
Therefore, a radar system which integrates the electronics and the antenna system into a compactly packaged radar system is desirable.